The structure of the egg-shell of Culex tritaeniorhynchus Giles is studied by sca-nning eletron microscopy.The egg-shell consists of three layers

the vitellinemembrane

the chorion shell and exochorion.The exochorion is structurallyslightly complex and on its surface there are many vertical projections modifiedin shapes and sizes.At the anterior end of the eggshell exists the micropilararea in which there is the micropyle with the radial grains around it.Atthe posterior end there is an irregular six-pointed star of about 14.410 μ indiameter

which has a hole with a plug near the centre of it.In the other partsof the surface including the lateral areas exist no special patterns of the proje-ctions.The patterns made up of the projections on the surfaces of the egg-shells ofdifferent genera or species of mosquitoes may be useful in taxonomy.